Lead times and build sequencing,
what fixes the order of work.

Build sequencing is the order in which the work on a house happens, and lead times are the waits that sit in front of that work, the period between committing to a material or a trade and having it on site ready to go. The two are one subject, because a sequence that ignores what takes longest to arrive is a wish list. Together they are the raw material of the build programme, the document at the centre of the scheduling reference this node belongs to.

Defined precisely, a task on a residential job can start when three conditions are met at once. The site is ready for it, the materials it needs have arrived, and the trade is booked and actually turns up. Only the first condition lives in the sequence; the second and third are procurement facts, decided weeks earlier by when an order was placed and when a booking was made. Most of what looks like a sequencing failure on site is one of those two conditions failing quietly upstream.

Why it matters

The sequence decides how long the job takes, and time on a residential job is money in a direct way, because preliminaries (supervision, site costs, hire) burn for every week the job runs. It also decides how many times each trade has to come back, which is where the quiet costs hide. A programme built from the real mechanisms holds together when the weather turns or a delivery slips; a programme built from habit produces a site where trades arrive to work that is not ready, and the builder pays for the difference.

Sequencing is the input to everything else the schedule does. The sequence and its dependencies determine which chain of tasks controls the finish date, the subject of the critical path and task dependencies, and the sequenced programme becomes the baseline that progress is later measured against. On the practical side, the residential construction scheduling guide covers building the programme itself; this node covers the reasoning underneath it, why the work goes in the order it does and what the waits in front of each stage actually are.

The sequence also reaches outside the cluster in both directions. Lead times connect it to procurement, because every need-on-site date in the programme implies an order-by date some weeks earlier. And the sequence begins before the site does; jobs commonly start late not because of earthworks but because variations and final pricing are still being settled in pre-construction, sometimes because the client is still changing scope, and in some cases legitimately because final pricing waits on the construction certificate. A start date promised while that paperwork is open is a sequencing decision made without its first dependency.

The sequence on paper assumes a clean handover between trades that reality rarely provides. The carpenter leaves one thing unfinished, the plumber needs one fitting that has not arrived, the room is ready except for the corner the other trade is still in, and each of those small frictions converts into the most expensive event in residential scheduling, another visit. Which is why experienced builders quietly stop scheduling in tasks and start scheduling in trade visits. The question is not whether the rough-in is on the programme; it is how many times the plumber will have to come to the job, and what each extra trip costs in mobilisation, booking-queue wait and goodwill.

Seen that way, the difference between a six-visit plumber and a four-visit plumber is usually the builder's sequencing, not the plumber. A visit splits when the work that could have been done together was not ready together, the bath not on site at rough-in, the tapware selection still open at fit-off, the other trade still occupying the wet area. Builders who plan each trade's visits deliberately, and hold the start conditions for each visit as one test, get fewer visits, keep their place in the trade's booking queue, and become the builder the good trades prefer to work for. The same visit-level view is what makes progress honest when it is measured against the baseline, covered in baselines and real progress tracking.

Where software fits the workflow

Traditionally the sequence lives in a bar chart that is rebuilt by hand every time the job moves, which is why so many programmes are quietly weeks out of date. In VIABUILD the programme is task-based with real dependencies, so when a stage slips the chain of dependent tasks moves with it and the affected trades and suppliers can be told from the task itself. The sequencing judgement stays with the builder; what changes is that the programme being judged against is current rather than reconstructed.

The sequence itself is working practice rather than a regulated document, but several Australian frameworks shape what it must contain. The points below are labelled by evidence class and are general information; requirements differ by state and change over time, so confirm the current position with your certifier, regulator or adviser before relying on any of them.

• Legislation. Each state and territory's building legislation prescribes mandatory inspection stages for residential work, commonly around footings or slab before the pour, frame, wet-area waterproofing in some jurisdictions, and final. The stages and who conducts them vary by jurisdiction, and each one is a hold point the programme has to carry. Confirm the current stages with your building surveyor or certifier.
• Government guidance. The National Construction Code (ABCB) sets the technical requirements, weatherproofing and wet-area waterproofing among them, that the sequenced work has to satisfy. Work that covers something an inspection needed to see gets reopened, which is a sequencing failure as much as a compliance one.
• Common practice. Standard domestic building contracts in most jurisdictions structure progress payments around named stages (commonly base, frame, lock-up, fixing and completion), so the build sequence and the job's cash flow are the same shape. A stage that slips takes its claim with it.
• Common practice. Concrete curing follows the engineer's specification and the relevant Australian Standards, and waterproofing membranes carry manufacturer cure times before covering. Neither is negotiable on site, so both belong in the programme as durations.
• Common practice. Wet seasons differ by region (summer in the north, winter across much of the south), and many builders sequence to reach roof cover or lock-up ahead of the local wet where the start date allows it.
• Common practice. Commencement commonly waits on paperwork rather than weather. Final pricing can legitimately depend on the construction certificate being issued, and open variations from late client scope changes hold the start date in a way clients do not always expect.

Illustrative only, not a benchmark. On a single-storey slab home, a plumber's work can in principle be done in four visits, under-slab drainage before the pour, a combined rough-in once the frame and roof are on, the fit-off after painting, and the final connection and test. Now watch the same scope on a loosely sequenced job. The rough-in visit happens, but the bath is not on site, so setting it becomes a fifth visit. At fit-off the client's tapware selection has arrived late and short, so the plumber fits what exists and returns a sixth time for the rest.

Same house, same plumber, same scope, two extra visits. Each one carries a mobilisation cost that someone absorbs, and a wait in the plumber's booking queue that the programme absorbs, and the second wait is usually the expensive one. Nothing here was the plumber's doing; the bath delivery and the selections deadline were both builder-side facts that were knowable weeks earlier. That is the practical meaning of sequencing in trade visits, the builder's job is to make each visit whole before booking it.

Sequence (the order of work on the job), lead time (the period from confirmed order to delivery), long-lead item (a package whose wait puts its order date on the critical path), lock-up (the shell closed against weather and entry), rough-in (services run through the open frame before linings), fit-off (fixtures and fittings installed at the finish), hold point (a mandatory inspection the work must not pass until it passes), trade stacking (multiple trades sharing one workface), trade visit (one mobilisation of one trade to site), practical completion (the works complete except for minor defects). The wider vocabulary lives in the construction glossary. From here, the natural next article is baselines and real progress tracking, how the sequence you committed to becomes the yardstick the job is measured against.

• National Construction Code (ABCB) , the technical requirements the sequenced work has to satisfy, weatherproofing and wet-area waterproofing among them.
• Your state or territory's building regulator and your building surveyor or certifier, for the mandatory inspection stages that apply to residential work in your jurisdiction.
• HIA and Master Builders Australia, for standard domestic building contracts and guidance on the named payment stages that mirror the build sequence.
• Your structural engineer's documentation and the product manufacturers' installation instructions, the primary record of curing, drying and covering requirements on your job.